1. Technical Field
The present invention relates to a semiconductor device and a method of manufacturing a semiconductor device, and relates to, for example, a semiconductor device in which a semiconductor chip is connected to an interconnect substrate in a flip-chip manner and a method of manufacturing a semiconductor device.
2. Related Art
There is flip-chip connection in one of the mounting types of a semiconductor chip. The flip-chip connection is a type in which an active surface of a semiconductor chip is caused to face an interconnect substrate, and then an electrode pad of the semiconductor chip and a terminal of the interconnect substrate are connected to each other through a solder. In recent years, in order to cope with the miniaturization of an electrode pad, a structure has been developed in which a Cu pillar is formed on the electrode pad, and the Cu pillar and the electrode pad are connected to each other by a solder. Here, as a solder, a Sn-based solder in which Pb is not used has been employed.
On the other hand, W. H. WU, and Three Others, “The influence of Current Direction on the Cu—Ni Cross-Interaction in Cu/Sn/Ni Diffusion Couples”, Journal of ELECTRONIC MATERIALS, Vol. 38, NO. 12, 2009 shows a result of examining electromigration when Sn is disposed between Cu and Ni. In this document, it is known that the distance between Cu and Ni is approximately 60 to 80 μm when seen from a photograph. In this condition, the formation of a void in Sn due to electromigration is reported.
When the Cu pillar is provided on the electrode pad, Cu diffuses from the Cu pillar to the Sn-based solder due to electromigration. When Cu diffuses to the Sn-based solder, an alloy Cu and Sn is formed, which leads to the formation of a void in the solder. When a void is formed in a solder, there is a high possibility of the solder being severed. Other problems and new features will be obvious from the description and the accompanying drawings of the present specification.